Neural mechanisms of perceptual localization

描述（由申请人提供）：实际上，每个视觉和视觉运动功能首先取决于视觉系统一致和准确定位刺激的能力，这在混乱和动态场景中尤其如此。然而，目前尚不清楚哪些类型的信息被整合来决定感知位置，这种整合是如何发生的，或者这一过程的神经机制和位点是什么。在典型的混乱和动态场景中，感知定位需要视觉系统分配和更新物体位置；要做到这一点，它不仅依赖于感兴趣的物体在视网膜上的位置，还主要依赖于四个额外的因素：视觉运动、参照系、偏心偏差、对比度适应。为了理解视觉系统是如何分配和更新物体位置的，我们必须将定位任务视为一个独立的过程，而不是一个依赖于场景中的上下文信息的综合过程。我们提出的实验有两个目标；首先，从心理物理角度测量感知位置作为视网膜位置、对比度适应、视觉运动、偏心偏差和参考框架的函数，以生成一个新的多因子整合场模型；我们将在fMRI实验中使用该模型来验证跨视觉皮层的神经主题组织是异质的（每个视觉区域中独特的位置代码）或同质的（跨视觉区域相同）的假设。我们的试验结果表明，在不同的视觉区域有独特的位置代码。该提案的第二个目标是测试这些独特的位置代码（地形组织的差异）是否具有感知后果。我们将使用心理物理学来测试这些预测的感知位置的双重分离，然后使用经颅磁刺激来测试异质视觉皮质地形组织对感知位置的因果贡献。我们方法的一个新颖之处在于开发了一种新的混合生成和判别空间编码模型，该模型可以同时应用于心理物理和功能磁共振成像数据，并进一步允许我们根据功能磁共振成像结果对特定情况下的感知结果做出预测。fMRI结果和知觉结果之间的因果关系将用TMS测试。我们的实验将提供关于线索如何被整合以确定视觉处理每个阶段的感知位置的新见解，这对于理解从弱视、黄斑变性到自闭症等一系列视觉和认知障碍中发生的基本定位缺陷至关重要。在我们了解典型大脑中的位置分配之前，我们缺乏必要的洞察力来开发诊断工具、预测标记和治疗这些损伤的结果措施。

DESCRIPTION (provided by applicant): Virtually every visual and visuomotor function hinges first and foremost on the visual system's ability to consistently and accurately localize stimuli, and this is especially true in cluttered and dynamic scenes. However, it is unknown what sorts of information are integrated to determine perceived position, how such integration occurs, or what the neural mechanism(s) and loci of this process are. Perceptual localization in typically cluttered and dynamic scenes requires the visual system to both assign and update object positions; to do this it relies not just on the retinal location of the object of interest, but als principally on four additional factors: visual motion, frames of reference, eccentricity biases, an contrast adaptation. To understand how the visual system assigns and updates object positions, we must approach the task of localization not as an isolated process, but as an integrative one-one that depends on contextual information in the scene. Our proposed experiments have two goals; first, to psychophysically measure perceived position as a function of retinal position, contrast adaptation, visual motion, eccentricity bias, and frames of reference in order to generate a novel multifactorial integration field model; we will use this model in fMRI experiments to test the hypothesis that neurotopic organization across visual cortex is heterogeneous (unique position codes in each visual area) or homogeneous (identical across visual areas). Our pilot results suggest that there are unique position codes in different visual areas. The second goal of the proposal is to test whether these unique position codes (the differences in topographic organization) have perceptual consequences. We will use psychophysics to test these predicted double dissociations in perceived location and then use TMS to test the causal contribution of heterogeneous visual cortical topographic organization to perceived position. One novelty of our approach lies in developing a new mixed generative and discriminative model of spatial coding, that can be applied to psychophysical and fMRI data in tandem, and further allows us to make predictions from fMRI results about perceptual outcomes in specific situations. The causal relationship between fMRI results and perceptual outcomes will then be tested with TMS. Our experiments will provide novel insight on how cues are integrated to determine perceived position at each stage of visual processing, which is crucial to understanding the fundamental localization deficits that occur in a range of visual and cognitive impairments ranging from amblyopia and macular degeneration, to autism. Until we understand how position is assigned in the typical brain, we lack the necessary insight to develop diagnostic tools, predictive markers, and treatment outcome measures for these impairments.